Method and device for joining members

ABSTRACT

A method for joining members of the present invention is as follows: a second member is inserted through a hole part of a first member; a guide shaft is inserted through a through hole of rubber; the rubber with the guide shaft inserted is inserted into the second member; and a drive mechanism relatively moves pushers and toward each other to compress the rubber in the extending direction of the guide shaft so that the rubber is expanded outward from inside to expand and deform at least a portion of the second member inserted into the hole part, thereby joining the second member to the first member.

TECHNICAL FIELD

The present invention relates to a method and a device for joiningmembers.

BACKGROUND ART

To reduce weight of automobiles and improve safety thereof, thin steelplates called high tension steels with high strength have been used.While these high tension steels are effective for weight reduction andsafety improvement, they are still heavy compared with low specificgravity materials such as aluminum. In addition, high tension steelshave problems such as deterioration of formability, increase of formingload, deterioration of dimensional accuracy, and the like, due to theirhigh strength. To solve these problems, multiple-material approach, inwhich an extrusion, a casting, and a press-formed part, using aluminumwith specific gravity less than that of a steel sheet, are used togetherwith a steel component, has been carried out in recent years.

In the multiple-material approach joining of a steel component and analuminum component involves problems. A brittle intermetallic compound(IMC) is generated in an interface between a steel plate and an aluminumplate in a welding technique typified by spot welding, so that joiningtechniques such as electromagnetic forming bonding, screw fasteningtypified by fastening with a bolt and a nut, friction stir welding(FSW), a riveting, a self-piercing riveting (SPR), mechanical clinching,adhesion, and the like are practically used.

In press-fitting by electromagnetic forming, a solenoid forming coil isinserted into a pipe-like part fitted to a mating part, and an inducedcurrent is induced in the pipe-like part being a conductor by a magneticfield changed by applying an impulse current to the solenoid formingcoil. An electromagnetic force is generated between a magnetic fieldgenerated by a primary current of the solenoid forming coil and theinduced current flowing in an opposite direction in a circumferentialdirection of the pipe-like part. At this time, the pipe-like partreceives a radially outward force, and the pipe-like part is deformedand expanded so as to be joined to the mating part by press-fitting.This joining method is suitable for copper and aluminum having goodelectric conductivity, and is also practically used in joining ofautomobile parts in some cases.

Patent Document 1 discloses a technique of press-fitting joining byelectromagnetic forming for multiple-material approach. Specifically, abumper reinforcement made of a shaped metal and having a hollow crosssection is deformed and expanded by electromagnetic forming, and thebumper reinforcement is fitted and joined to a hole provided in a bumperstay made of an aluminum alloy.

PRIOR ART DOCUMENT Patent Document

Patent Document 1: JP 2007-284039 A

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

As in Patent Document 1, electromagnetic forming is suitable for joininga hollow part made of copper or aluminum having good electricalconductivity to a mating part by press-fitting, and a circular shape ispreferable due to its joining mechanism.

Unfortunately, joining by electromagnetic forming requires use of asolenoid coil smaller than an inner diameter of an aluminum part(aluminum pipe). Reducing a diameter of a coil when a small diameterpart is joined has problems of difficulty in manufacturing of the coil,and performance and durability thereof. Particularly, regarding thedifficulty in manufacturing, it is difficult to form a conductor into acoil shape, so that restrictions on a material and a cross-sectionalshape of the conductor are strict. When the conductor is formed into acoil shape, a cross section of the conductor is deformed. In addition,additional capital investment for high voltage capacitors with largecapacity or the like, is required. Further, the joining byelectromagnetic forming cannot be applied to an aluminum part providedwith a rectangular cross section, a hole, or a slit.

Even in press-fitting joining other than electromagnetic forming,members may be limited in shape. For example, elongated members cannotbe disposed in a joining device such as a press machine, and thus cannotbe joined by press-fitting.

It is an object of the present invention to provide a method for joiningmembers, capable of joining two members, particularly elongated members,at low cost without being limited in shape and material of the memberswhile reducing a load on each member and increasing joining strength.

Means for Solving the Problems

A first aspect of the present invention provides a method for joiningmembers including: providing a first member formed with a hole part, ahollow second member, an elastic body having a through hole, a pair ofpushers that are disposed on both sides of the elastic body and thatsupport a guide shaft extending in a horizontal direction and aremovable in the guide shaft extending direction, and a drive mechanismfor relatively moving the pair of pushers toward each other in the guideshaft extending direction; inserting the second member into the holepart of the first member; inserting the guide shaft into the throughhole of the elastic body; inserting the elastic body, through which theguide shaft passes, into the second member; and relatively moving thepair of pushers toward each other by the drive mechanism to compress theelastic body in the guide shaft extending direction to expand theelastic body outwardly, thereby expanding and deforming at least aportion of the second member inserted into the hole part to join thesecond member to the first member by press-fitting.

According to this method, the elastic body is expanded radially outwardto uniformly expand and deform the second member, so that localdeformation can be prevented and a load on each member can be reduced.This is because the second member can be uniformly deformed by usingproperties of the elastic body that uniformly expands outward fromradially inside after compressed in a guide shaft direction. Thisenables fitting accuracy to be improved to increase joining strength. Inaddition, this method is also simpler than electromagnetic forming andother processing methods. Electromagnetic forming is usable only forconductive materials, and is limited in cross-sectional shape anddimension of a conductor depending on a coil to be used. In contrast,this method has no limitations with respect to_cross-sectional shape orsize of the members, regardless of their materials. In addition, thereis no need for electrical equipment requiring a capacitor with largecapacity, and it is possible to join two members at low cost. Inparticular, the elastic member is laterally supported by the guideshaft, and the second member is joined by press-fitting by moving thepusher in a horizontal direction (the guide shaft extending direction)to compress the elastic member, so that the second member can bedisposed laterally. Thus, even an elongated second member can be joinedby press-fitting. Here, the horizontal direction in which the guideshaft extends includes an inclined direction in addition to a stricthorizontal direction.

It is preferable that the drive mechanism includes a cam mechanism forconverting a force applied in a direction different from the guide shaftextending direction to a force in the guide shaft extending direction,and that the elastic body is compressed by the force of which thedirection has been converted by the cam mechanism.

The cam mechanism enables the second member to be disposed in thehorizontal direction with equipment for applying a compressive force ina normal vertical direction, so that the second member can be joined bypress-fitting without being limited in shape. In particular, when thesecond member is long, ordinary equipment for applying a compressiveforce cannot join the second member by press-fitting due to limitationon dimension, however, the present structure enables the second memberto be joined by press-fitting even when the second member is long.

It is preferable that the drive mechanism includes an urging portionthat urges one of the pushers outwardly in the guide shaft extendingdirection, and that after the elastic body is compressed in the guideshaft extending direction, the one of the pushers is returned by theurging portion.

The pusher is automatically returned to its original position by theurging portion, so that there is no need to manually return the pusherto the original position, thereby workability can be improved.

It is preferable that one of the pair of pushers is fixed.

When one of the pushers is fixed, the driving mechanism needs to beprovided only for the pusher on one side, and thus structure of thedrive mechanism can be simplified. In addition, movement of the firstmember and the second member can be limited so that workability can beimproved.

It is preferable that there is further provided a guide shaft movingmechanism for moving the guide shaft in the horizontal direction isfurther prepared, and that the elastic body, through which the guideshaft passes, is inserted into the second member by the guide shaftmoving mechanism.

Since the guide shaft moving mechanism moves the guide shaft in thehorizontal direction, the guide shaft and the elastic body can bereliably inserted into the second member.

A second aspect of the present invention provides a device for joiningmembers to join a first member formed with a hole part and a hollowsecond member by press-fitting using an elastic body having a throughhole comprising: a pair of pushers which support a guide shaft extendingin a horizontal direction, the pair of pushers being disposed on bothsides of the elastic body and being movable in the guide shaft extendingdirection; and a drive mechanism for relatively moving the pair ofpushers toward each other in the guide shaft extending direction,wherein the pushers are driven by the drive mechanism, with the secondmember being inserted through the hole part of the first member topenetrate the first member, with the guide shaft being inserted throughthe through hole of the elastic body, and with the elastic body throughwhich the guide shaft is inserted being inserted in the second member,such that the elastic body is compressed in the guide shaft extendingdirection and expanded outwardly, so as to expand and deform at least aportion of the second member inserted into the hole part to join thesecond member to the first member by press-fitting.

Effect of the Invention

According to the present invention, the elastic body is expanded outwardfrom inside to uniformly expand and deform the second member, so thatlocal deformation can be prevented and a load on each member can bereduced. This enables fitting accuracy to be improved to increasejoining strength. In addition, this method is simpler thanelectromagnetic forming and other processing methods, so that twomembers can be joined to each other at low coat without being limited inshape and material. In particular, the second member can be disposedlaterally, so that even an elongated member can be joined.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1A is a partial cross-sectional view before joining bypress-fitting according to a first embodiment of the present invention;

FIG. 1B is a partial cross-sectional view after joining by press-fittingaccording to a first embodiment of the present invention;

FIG. 2A is a partial cross-sectional view before joining bypress-fitting of a type in which a guide shaft rotates;

FIG. 2B is a partial cross-sectional view before joining bypress-fitting of a type in which the guide shaft rotates;

FIG. 3A is a partial cross-sectional view before joining bypress-fitting of an another type in which the guide shaft rotates;

FIG. 3B is a partial cross-sectional view after joining by press-fittingof an another type in which the guide shaft rotates;

FIG. 4 is a cross-sectional view showing a second member having apartition wall and a rubber inserted in the second member;

FIG. 5A is a partial cross-sectional view before joining bypress-fitting in which a plurality of guide shafts are inserted into thesecond member having the partition wall;

FIG. 5B is a partial cross-sectional view after joining by press-fittingin which a plurality of guide shafts are inserted into the second memberhaving the partition wall;

FIG. 6A is a perspective view in the case where the shape of the hole ofthe first member and the cross-sectional shape of the second member aresimilar;

FIG. 6B is a perspective view in the case where the shape of the hole ofthe first member and the cross-sectional shape of the second member arenon-similar;

FIG. 7A is a perspective view before joining by press-fitting in whichthe first member has a hat shape;

FIG. 7B is a perspective view after joining by press-fitting in whichthe first member has a hat shape;

FIG. 8A is a partial cross-sectional view before joining bypress-fitting in which the first member is burred;

FIG. 8B is a partial cross-sectional view after joining by press-fittingin which the first member is burred;

FIG. 9A is a view before joining by press-fitting in the case where anouter frame metal mold is disposed around the second member;

FIG. 9B is a view after joining by press-fitting in the case where anouter frame metal mold is disposed around the second member;

FIG. 10A is a partial cross-sectional view before joining bypress-fitting in which the rubber in the joint portion between the firstmember and the second member is separated;

FIG. 10B is a partial cross-sectional view after joining bypress-fitting in which the rubber in the joint portion between the firstmember and the second member is separated;

FIG. 11A is a partial cross-sectional view showing the first step ofjoining by press-fitting according to a second embodiment of the presentinvention;

FIG. 11B is a partial cross-sectional view showing the second step ofjoining by press-fitting according to a second embodiment of the presentinvention;

FIG. 11C is a partial cross-sectional view showing the third step ofjoining by press-fitting according to a second embodiment of the presentinvention;

FIG. 11D is a partial cross-sectional view showing the forth step ofjoining by press-fitting according to a second embodiment of the presentinvention;

FIG. 11E is a partial cross-sectional view showing the fifth step ofjoining by press-fitting according to a second embodiment of the presentinvention;

FIG. 12A is a partial cross-sectional view before joining bypress-fitting according to a third embodiment of the present invention;and

FIG. 12B is a partial cross-sectional view after joining bypress-fitting according to a third embodiment of the present invention.

MODE FOR CARRYING OUT THE INVENTION

Embodiments of the present invention will be described below withreference to the accompanying drawings. In each of the embodimentsdescribed below, a first member 10 and a second member 20 are notparticularly limited in material, so that the present invention can beapplied to any material.

First Embodiment

A method of joining the first member 10 and the second member 20 to eachother using a press-fitting apparatus 30 will be described withreference to FIGS. 1A and 1B. In the press-fitting apparatus 30 of thepresent embodiment, the first member 10 and the second member 20 arejoined by a press-fitting using rubber (elastic body) 32, a pair ofpushers 34 a and 34 b, and a drive mechanism 36.

The first member 10 is a hollow pipe type, and is disposed so as toextend in a horizontal direction.

The second member 20 has a closed cross section, and includes end walls14 and 14 provided with two respective holes 12 and 12 passingtherethrough laterally, and two side walls 16 and 16 connecting the twoend walls 14 and 14.

The rubber 32 is a hollow pipe type extending in the horizontaldirection, and is provided at its center with a through hole 32 a (referto FIG. 4) for allowing a guide shaft 38 to be inserted thereinto. Therubber 32 is supported by the guide shaft 38 when the guide shaft 38 isinserted into the through hole 32 a (refer to FIG. 4), and is maintainedin posture and position. As a material of the rubber 32, it ispreferable to use any one of urethane rubber, chloroprene rubber, CNRrubber (chloroprene rubber+nitrile rubber), and silicone rubber, forexample. It is preferable that the rubber 32 has a Shore A hardness of30 or more.

The pair of pushers 34 a and 34 b are disposed on both sides of therubber 32, having a substantially columnar shape extending in thehorizontal direction, and press the rubber 32 from both the sides tocompress it. The pushers 34 a and 34 b respectively have pressingsurfaces 34 c and 34 d that are formed flat, so that a load is uniformlyapplied to the rubber 32 when the rubber 32 is compressed. In thepresent embodiment, the one pusher 34 a is fixed so as not to move withrespect to the guide shaft 38. The other pusher 34 b has an insertionhole (not illustrated) through which the guide shaft 38 is inserted.When the guide shaft 38 is inserted through the insertion hole (notillustrated), the pusher 34 b is movable along the guide shaft 38. Theother pusher 34 b is attached to the drive mechanism 36, and thus ismoved in the horizontal direction along the guide shaft 38 by the drivemechanism 36.

The drive mechanism 36 includes a cam driver 40 and a cam slider 42. Thecam slider 42 has an insertion hole (not illustrated) through which theguide shaft 38 is inserted, and is movable along the guide shaft 38 in astate where the guide shaft 38 is inserted through the insertion hole.

The pusher 34 b is attached to the cam slider 42 such that the insertionhole of the cam slider 42 and the insertion hole of the pusher 34 b areconcentric with each other. Thus, the pusher 34 b is movable along theguide shaft 38 together with the cam slider 42 in a state where theguide shaft 38 is inserted through the insertion hole of the cam slider42 and the insertion hole of the pusher 34 b.

The cam slider 42 is provided on its upper portion with an inclinedsurface 42 a for receiving a force from the cam driver 40. The camdriver 40 is movable in a vertical direction, and is provided on itslower portion with an inclined surface 40 a for transmitting a force tothe cam slider 42. When a downward force is applied to the cam driver40, the force is transmitted from the cam driver 40 to the cam slider 42via the inclined surfaces 40 a and 42 a. Then, the cam driver 40 ismoved in the vertical direction (downward in the drawing), and the camslider 42 is moved in the horizontal direction (the left direction inthe drawing) along the guide shaft 38. That is, the drive mechanism 36of the present embodiment has a cam mechanism composed of the cam slider42 and the cam driver 40. For the cam driver 40, a press machine or thelike that is usually used for press working or the like may be used, forexample.

The drive mechanism 36 is provided on its outer side in the horizontaldirection (the right side in the drawing) with a vertical wall portion44 for stopping an outward movement of the drive mechanism 36 in thehorizontal direction. The vertical wall portion 44 is provided with aninsertion hole (not illustrated) through which the guide shaft 38 isinserted, and the guide shaft 38 extends outward in the horizontaldirection of the vertical wall portion 44 through the insertion hole.Thus, the guide shaft 38 includes one end 38 a that is fixed withrespect to the guide shaft 38 together with the one pusher 34 a, and theother end 38 b that is fixed with respect to the guide shaft 38 on anouter side in the horizontal direction of the vertical wall portion 44.

The vertical wall portion 44 and the cam slider 42 are elasticallyconnected by a coil spring (urging portion) 46, and the cam slider 42 isurged toward the vertical wall portion 44.

The first member 10 and the second member 20 are joined to each other bypress-fitting in the following procedure.

First, the second member 20 is inserted through the hole part 12 of thefirst member 10, and the guide shaft 38 is inserted through the throughhole 32 a of the rubber 32. Subsequently, the rubber 32 with the guideshaft 38 inserted is inserted into the second member 20, and the pushers34 a and 34 b are disposed on respective sides of the rubber 32, andthen both the ends 38 a and 38 b of the guide shaft 38 are fixed. Atthis time, the one pusher 34 a is fixed so as not to move with respectto the guide shaft 38, and the other pusher 34 b is disposed to bemovable along the guide shaft 38 by the drive mechanism 36. FIG. 1Ashows the state at this time.

Next, a downward force is applied to the cam driver 40 of the drivemechanism 36 to move the cam driver 40 downward so that a force istransmitted to the cam slider 42 from the cam driver 40 via the inclinedsurfaces 40 a and 42 a. Then, a force in the vertical direction(downward in the drawing) is converted to a force in the horizontaldirection (the left direction in the drawing). The cam slider 42 ismoved in an extending direction of the guide shaft 38, for compressingthe rubber 32. The one pusher 34 a is fixed with respect to the guideshaft 38, and the other pusher 34 b is moved together with the camslider 42 in the left direction along the guide shaft 38. As a result,the pushers 34 a and 34 b move relatively closer each other, so that therubber 32 is compressed in the extending direction of the guide shaft 38to be expanded outward from radially inside. As described above, atleast a portion of the second member 20 inserted through the hole part12 is expanded and deformed, so that the second member 20 is joined tothe first member 10 by press-fitting. FIG. 1B shows the state at thistime.

While there is no illustration, when the cam driver 40 of the drivemechanism 36 is moved upward after joining by press-fitting, a forceapplied to the cam slider 42 in the horizontal direction (the leftdirection in the drawing) is removed. Then, the cam slider 42 isreturned to an original position by the coil spring 46. At the time, therubber 32 expanded in the second member 20 is returned to a naturalstate from a state expanded radially when a force applied thereto isremoved, and its contact with the second member 20 is released. Thus,the first member 10 and the second member 20 joined by press-fitting canbe easily removed from the press-fitting apparatus 30 without receivingfrictional force from the rubber 32.

As described above, when the rubber 32 is expanded radially outward touniformly expand and deform the second member 20, so that localdeformation can be prevented and a load on each of the members 10 and 20can be reduced. This is because the second member 20 can be uniformlydeformed by using properties of the rubber 32 that uniformly expandsoutward from radially inside after compressed in the extending directionof the guide shaft 38. This enables fitting accuracy to be improved toincrease joining strength. In addition, this method is also simpler thanelectromagnetic forming and other processing methods. Electromagneticforming can be used only for a conductive material, and is limited incross-sectional shape and dimension of a conductor depending on a coilto be used. In contrast, this method has no limitations with respectto_cross-sectional shape or size, regardless of its material. Inaddition, there is no need for electrical equipment requiring acapacitor with large capacity, and it is possible to join the twomembers 10 and 20 at low cost. In particular, the rubber 32 is laterallysupported by the guide shaft 38, and the second member 20 is joined bypress-fitting by moving the pushers 34 a and 34 b in the horizontaldirection (the extending direction of the guide shaft 38) to compressthe rubber 32, so that the second member 20 can be disposed laterally.Thus, even an elongated second member 20 can be joined by press-fitting.Here, the horizontal direction in which the guide shaft 38 extendsincludes an inclined direction in addition to a strict horizontaldirection.

The cam mechanism of the drive mechanism 36 enables the second member 20to be disposed in the horizontal direction with equipment for applying acompressive force in a vertical direction, which is often used in anormal press machine or the like, so that the second member 20 can bejoined by press-fitting without being limited in shape. In particular,when the second member 20 is long, ordinary equipment for applying acompressive force cannot join the second member by press-fitting due tolimitation on dimension, however, the present structure enables thesecond member 20 to be joined by press-fitting even when the secondmember 20 is long.

In addition, the cam slider 42 and the pusher 34 b are automaticallyreturned to their original positions by the coil spring 46, so thatthere is no need to manually return the cam slider 42 and the pusher 34b to the original positions, thereby workability can be improved.

When one pusher 34 a is fixed with respect to the guide shaft 38, thedrive mechanism 36 needs to be provided only for the other pusher 34 b,thereby enabling the drive mechanism 36 to be simplified in structure.In addition, movement of the first member 10 and the second member 20can be limited so that workability can be improved.

FIGS. 2A and 2B each illustrate a press-fitting apparatus 30 of a typein which a guide shaft rotates. The press-fitting apparatus 30 includesa drive mechanism 36 that does not have a cam slider 42 and a cam driver40 as described above. The press-fitting apparatus 30 applies rotationaltorque to the guide shaft 38 so that the pushers 34 a and 34 b moverelatively closer each other in the horizontal direction in aninterlocked manner to compress the rubber 32.

In the press-fitting apparatus 30, the guide shaft 38 is provided withthread grooves 38 c and 38 d, and two support rods 48 and 48 passthrough the pushers 34 a and 34 b, and the rubber 32. Thus, the pushers34 a and 34 b, and the rubber 32 have respective insertion holes (notillustrated) corresponding to the support rods 48 and 48 passingtherethrough.

When the guide shaft 38 is rotated as indicated by an arrow in thedrawing, rotational torque is transmitted to the pushers 34 a and 34 bvia the thread grooves 38 c and 38 d, respectively. However, the supportrods 48 and 48 stop rotation of the pushers 34 a and 34 b, respectively,so that the pushers 34 a and 34 b are respectively moved along thethread grooves 38 c and 38 d of the guide shaft 38 without rotating. Thethread groove 38 c and 38 d do not have the same shape, and are formedin shapes different from each other for the respective pushers 34 a and34 b to move the pushers 34 a and 34 b closer to each other.

As described above, the press-fitting apparatus 30 applies rotationaltorque to the guide shaft 38 to move the pushers 34 a and 34 b closer toeach other so that the rubber 32 is compressed in the horizontaldirection to be expanded radially. As a result, the first member 10 andthe second member 20 are joined to each other by press-fitting.

FIGS. 3A and 3B each illustrate a press-fitting apparatus 30 of anothertype in which a guide shaft rotates. While the press-fitting apparatus30 of each of FIGS. 2A and 2B is provided with the thread grooves 38 cand 38 d (refer to FIGS. 2A and 2B) so that the pushers 34 a and 34 b onrespective sides move closer to each other, the press-fitting apparatus30 of each of FIGS. 3A and 3B has one pusher 34 a that is fixed withrespect to a guide shaft 38. A thread groove 38 d is formed on only oneside with respect to a joint portion so that the other pusher 34 b ismoved in a horizontal direction along the guide shaft 38. In addition, apushing fixture 50 is provided on a laterally outer side (the right sidein the drawing) of the pusher 34 b to be laterally moved with rotationof the guide shaft 38 to laterally push and move the other pusher 34 b.Support rods 48 and 48 pass through the pushing fixture 50. When theguide shaft 38 is rotated, rotational torque is transmitted to thepushing fixture 50 via the thread groove 38 d. However, the support rods48 and 48 stop rotation of the pushing fixture 50, so that the pushingfixture 50 is moved along the thread groove 38 d of the guide shaft 38without rotating. Thus, the other pusher 34 b is pushed by the pushingfixture 50, and is moved along the guide shaft 38 to approach the onepusher 34 a fixed with respect to the guide shaft 38.

As described above, in the press-fitting apparatus 30, as the guideshaft 38 is rotated, the other pusher 34 b approaches the one pusher 34a, so that the rubber 32 is laterally compressed to be expandedradially. As a result, a first member 10 and a second member 20 arejoined to each other by press-fitting.

FIGS. 4 to 5B each illustrate a press-fitting apparatus 30 in which asecond member 20 has partition walls 22, and a plurality of guide shafts38 are provided. Forms of rubber 32 and the second member 20 can bevariously modified. As illustrated in FIG. 4, the second member 20 mayhave a rectangular outer shape, and have partition walls 22 dividing itsinside into four. This case requires also four pieces of rubber 32 andfour guide shafts 38, to be inserted into the second member 20.

When the partition walls 22 are provided as described above, the secondmember 20 can be increased in strength. In addition, a cross-sectionalshape of the second member 20 is not limited to a rectangular, and mayhave any shape. Further, the partition walls 22 are not particularlylimited in shape, and may have a shape dividing the second member 20into two, for example.

As illustrated in FIGS. 5A and 5B, while there is a plurality of guideshafts 38 and 38 and pushers 34 a and 34 b, the structure of other partsis the same as that of the present embodiment. As described above, thepresent invention is also applicable even when the second member 20 hasthe partition walls 22.

As illustrated in FIGS. 6A and 6B, the first member 10 and the secondmember 20 can be variously changed in form. It is preferable that thesecond member 20 has a cross-sectional shape similar to the hole part 12of the first member 10 (e.g., a circular shape), as illustrated in FIG.6A. When the hole part 12 of the first member 10 and a cross-section ofthe second member 20 are similar to each other in shape, the secondmember 20 can be uniformly expanded and deformed to be joined to thefirst member 10. As a result, a local load can be prevented from beingapplied to the first member 10 and the second member 20. However, asillustrated in FIG. 613, the present invention is applicable even whenthe hole part 12 of the first member 10 and the cross-section of thesecond member 20 are not similar in shape (e.g., circular and squareshapes).

As illustrated in FIGS. 7A and 7B, two or more joint portions betweenthe first member 10 and the second member 20 may be provided. In thecase of joining at two places, the first member 10 may have a hat shapeas illustrated in FIGS. 7A and 7B, or may have another shape. It ispreferable that burring is applied to the hole part 12 of the firstmember 10, as illustrated in FIGS. 8A and 8B. This is because strengthof the hole part 12 of the first member 10 can be increased by burringan edge of the hole part 12 of the first member 10. As a result,deformation of the first member 10 and damage to the second member 20due to deformation of the first member 10 can be prevented, and joiningstrength can be increased by increasing a joining area by burring.

As illustrated in FIGS. 9A and 9B, the first member 10 and the secondmember 20 may be joined by press-fitting by using an outer frame mold52. The outer frame mold 52 may have a cylindrical shape concentric withthe second member 20. The outer frame mold 52 is disposed radiallyoutward of the second member 20. In a state before the rubber 32 islaterally compressed to be expanded radially outward, as illustrated inFIG. 9A, a gap is provided between the second member 20 and the outerframe mold 52. When the rubber 32 is expanded radially outward by thepushers 34 a and 34 b from this state, as illustrated in FIG. 9B, thesecond member 20 can coincide with an inner surface shape of the outerframe mold 52 when being expanded and deformed.

As illustrated in FIGS. 10A and 10B, the rubber 32 may be separated nearthe hole part 12. When the rubber 32 is separated at the hole part 12,or at a joint portion, deformation of the hole part 12 of the firstmember 10 can be prevented. Specifically, the rubber 32 is separated, sothat no enlarging deforming force is applied to the hole part 12 toenable an original shape of the hole part 12 to be maintained.

Second Embodiment

A method for joining by press-fitting of the present embodimentillustrated in FIGS. 11A to 11E uses the same structure as that of thefirst embodiment of FIGS. 1A and 1B other than parts related to a pusher(guide shaft moving mechanism) 54. Accordingly, parts similar to thoseillustrated in FIGS. 1A and 1B are denoted by the same referencenumerals, and description thereof may be eliminated.

FIGS. 11A to 11E illustrate first to fifth steps of the presentembodiment, respectively. In the present embodiment, wheels 56 areprovided at a lower end of each of a cam slider 42 and a vertical wallportion 44, so that the cam slider 42 and the vertical wall portion 44are movable in a horizontal direction. In addition, a cam driver 40 isalso movable in the horizontal direction by a rail mechanism (notillustrated) or the like.

The pusher 54 is provided on the lateral outer side of the vertical wallportion 44. The pusher 54 supports a guide shaft 38 and moves the guideshaft 38 in the horizontal direction. A method for allowing the pusher54 to move the guide shaft 38 is not particularly limited, and the guideshaft 38 may be fed out or drawn using a motor, a gear, or the like, forexample.

The vertical wall portion 44 is fixed with respect to the guide shaft38, and is moved together with the guide shaft 38 by the pusher 54.Accordingly, the vertical wall portion 44, the drive mechanism 36, and apair of pushers 34 a and 34 b are moved together without changing theirrelative positions in the horizontal direction, with a movement of theguide shaft 38.

FIG. 11A illustrates a first step where the second member 20 is insertedthrough the hole part 12 of the first member 10. FIG. 11B illustrates asecond step where the rubber 32 is inserted into the second member 20 bythe pusher 54. FIG. 11C illustrates a third step where a compressiveforce is applied to the rubber 32 in an extending direction of the guideshaft 38 by the drive mechanism 36 to expand the rubber 32 radiallyoutward, so that the first member 10 and the second member 20 are joinedto each other by press-fitting. FIG. 11D illustrates a fourth step wherethe compressive force in the extending direction of the guide shaft 38applied by the drive mechanism 36 is removed, so that the rubber 32returns to its natural state. FIG. 11E illustrates a fifth step wherethe pusher 54 moves the press-fitting apparatus 30, so that the rubber32 is pulled out from the second member 20.

As described above, since the pusher 54 moves the guide shaft 38 in thehorizontal direction, the guide shaft 38 and the rubber 32 can bereliably inserted into the second member 20.

Third Embodiment

FIGS. 12A and 12B each illustrate a method for joining according to thepresent embodiment that uses structure similar to that of the firstembodiment of each of FIGS. 1A and 1B other than parts related tostructure in which pushers 34 a and 34 b on both sides are movedtogether to compress rubber 32 in a horizontal direction. Accordingly,parts similar to those illustrated in FIGS. 1A and 1B are denoted by thesame reference numerals, and description thereof may be eliminated.

In the present embodiment, two drive mechanisms 36 and 36, and twovertical wall portions 44 and 44 are provided. The pair of pushers 34 aand 34 b are attached together to a cam slider 42, and are not fixedwith respect to the guide shaft 38. This causes both the pushers 34 aand 34 b to move closer to each other in the horizontal direction by thedrive mechanisms 36 and 36, respectively, so that the rubber 32 iscompressed in an extending direction of the guide shaft 38.

Whether to use a one-side access type in which one side pusher 34 b ismoved with respect to rubber 32 as in the first and second embodiments,or a two-side access type in which pushers 34 a and 34 b on respectivesides are moved with respect to rubber 32 as in the third embodiment,can be appropriately determined depending on a mode and application ofjoining by press-fitting.

DESCRIPTION OF SYMBOLS

-   10 First member-   12 Hole part-   14 End wall-   16 Side wall-   20 Second member-   22 Partition wall-   30 Press-fitting apparatus-   32 Rubber-   32 a Through hole-   34 a, 34 b Pusher-   34 c, 34 d Pressing surface-   36 Drive mechanism-   38 Guide shaft-   38 a One end-   38 b The other end-   38 c, 38 d Thread groove-   40 Cam driver-   40 a Inclined surface-   Cam slider-   42 a Inclined surface-   44 Vertical wall portion-   46 Coil spring (urging portion)-   48 Support rod-   50 Pushing fixture-   52 Outer frame mold-   54 Pusher (guide shaft moving mechanism)-   56 Wheel

1. A method for joining members comprising: providing a first memberformed with a hole part, a hollow second member, an elastic body havinga through hole, a pair of pushers which are disposed on both sides ofthe elastic body and which support a guide shaft extending in ahorizontal direction and are movable in the guide shaft extendingdirection, and a drive mechanism for relatively moving the pair ofpushers toward each other in the guide shaft extending direction;inserting the second member into the hole part of the first member;inserting the guide shaft into the through hole of the elastic body;inserting the elastic body, through which the guide shaft passes, intothe second member; and relatively moving the pair of pushers toward eachother by the drive mechanism to compress the elastic body in the guideshaft extending direction to expand the elastic body outwardly, therebyexpanding and deforming at least a portion of the second member insertedinto the hole part to join the second member to the first member bypress-fitting.
 2. The method for joining members according to claim 1,wherein the drive mechanism includes a cam mechanism for converting aforce applied in a direction different from the guide shaft extendingdirection to a force in the guide shaft extending direction, and whereinthe elastic body is compressed by the force of which the direction hasbeen converted by the cam mechanism.
 3. The method for joining membersaccording to claim 1, wherein the drive mechanism includes an urgingportion that urges one of the pushers outwardly in the guide shatextending direction, and wherein after the elastic body is compressed inthe guide shat extending direction, the one of the pushers is returnedby the urging portion.
 4. The method for joining members according toclaim 1, wherein one of the pair of pushers is fixed.
 5. The method forjoining members according to claim 1, further comprising, providing aguide shaft moving mechanism for moving the guide shaft in thehorizontal direction, wherein the elastic body, through which the guideshaft passes, is inserted into the second member by the guide shaftmoving mechanism.
 6. A device for joining members to join a first memberformed with a hole part and a hollow second member by press-fittingusing an elastic body having a through hole comprising: a pair ofpushers which support a guide shaft extending in a horizontal direction,the pair of pushers being disposed on both sides of the elastic body andbeing movable in the guide shaft extending direction; and a drivemechanism for relatively moving the pair of pushers toward each other inthe guide shaft extending direction, wherein the pushers are driven bythe drive mechanism, with the second member being inserted through thehole part of the first member to penetrate the first member, with theguide shaft being inserted through the through hole of the elastic body,and with the elastic body through which the guide shaft is insertedbeing inserted in the second member, such that the elastic body iscompressed in the guide shaft extending direction and expandedoutwardly, so as to expand and deform at least a portion of the secondmember inserted into the hole part to join the second member to thefirst member by press-fitting.
 7. The method for joining membersaccording to claim 2, wherein the drive mechanism includes an urgingportion that urges one of the pushers outwardly in the guide shatextending direction, and wherein after the elastic body is compressed inthe guide shat extending direction, the one of the pushers is returnedby the urging portion.
 8. The method for joining members according toclaim 2, wherein one of the pair of pushers is fixed.
 9. The method forjoining members according to claim 2, further comprising, providing aguide shaft moving mechanism for moving the guide shaft in thehorizontal direction, wherein the elastic body, through which the guideshaft passes, is inserted into the second member by the guide shaftmoving mechanism.